Thermal relays have been well known for many years. Typical prior art thermal relays have included a bimetal actuator in close proximity to an electric heater which causes the bimetal actuator to bend and actuate one or more sets of electrical contacts when heated by the electric heater. The problem with prior art devices lies in the fact that heat is continuously supplied to the bimetal actuator. Thus, when it comes time to deenergize the prior art thermal relay, it is necessary for the bimetal actuator to cool before the relay contacts will be deactuated. Thus, a substantial amount of time is involved between the time current to the heater is interrupted and the time the thermal relay contacts are deenergized. This delay time in deenergizing and the delay time in energizing has severely restricted the use of thermal relays.
In the past few model years, automobiles have included a cornering lamp in the signal light system. The cornering lamps are placed on the side of the front fender of the automobile and are continuously energized when the turn signal switch is actuated by the driver. Generally, the cornering lamp is energized by a thermal relay which, in turn, is intermittently energized by the turn signal flasher. It is necessary, of course, that the cornering lamp be energized relatively soon after the turn signal switch is actuated, that it remain energized during the entire period of time the turn signal switch is closed, and that it be deenergized relatively soon after the turn signal switch is opened. Typical opening and closing times for the cornering relay are that the contacts close within 2.5 seconds after application of power and that after the contacts have remained closed for 30 seconds or more that they open within 7 seconds after power is interrupted. While the closing time has not provided any substantial problem, the opening time has been difficult to meet.